Recombinant human TSH in radioiodine treatment of differentiated thyroid cancer

Recombinant human TSH (rhTSH) has been developed to facilitate the follow-up for persistent or recurrent differentiated thyroid cancer (DTC), avoiding the hypothyroid symptoms after the withdrawal of Levothyroxine (L-T4) suppressive therapy.

To analyse the effect of rhTSH in providing stimulation of radioiodine uptake (RAIU) for the ablation of thyroid remnant and/or malignant thyroid tissue in patients with metastatic DTC. Ten subjects (4 women, 6 men), mean age 53 years, with DTC (7 papillary, 2 follicular and 1 Hürthle-cell), requiring radioiodine therapy (RIT) were studied. Nine of them had a positive diagnostic whole body scan (dWBS) or CT for thyroid remnant, lymph nodes and/or distant metastases. One patient with an invasive tall cell PTC had an increased serum Tg and a negative dWBS. Serum TSH was measured before and two days after the rhTSH injection. Thyroglobulin measurements were performed before the rhTSH administration, 3 and 6 months after RIT. There were no serious side effects of the rhTSH application.

Serum TSH after the rhTSH injection rose to 156.5 +/- +/- 60.9 mIU/L and induced RAIU in 8 out of 10 patients. Basal serum Tg was increased in 6 patients and decreased three months later in 2 of them. The post-therapy WBS (pthWBS) showed: 1) additional metastatic lesions in 3 patients with positive dWBS, 2) lung nodular metastases in 1 patient with negative dWBS, 3) similar image as the dWBS in 4 patients, 4) negative image in 1 patient with positive dWBS.

RhTSH is a safe and promising method for the stimulation of RAIU in patients with thyroid remnant and/or persistent or recurrent DTC, avoiding L-T4 withdrawal.